removal of old badly rusted set screws

[ad356]

im working on a K301 that belongs to a cub cadet 124. this is an unfinished project i would like to finish. several years ago i stripped, sandblasted, and painted the frame and sheet metal. it has sat up in my loft for the last couple of years and i really havent done much to it since. i have a narrow frame hydrualic lift unit, a NOS 48" mower deck pan, nice headlight panel, 3 pt hitch, and a creaper gear that can go on this when done. i would be a nice rig.

so i have to address the engine. this tractor sat out in a field in the weather for many years so everything was pretty heavily rusted. i have to remove the PTO and generator drive pulleys. i tried using the normal hex keys and forget it, they arent going to move. the hex isnt much of a hex anymore and i cant get a bite. so next step was to use an extractor not sure if that going to work either. should i just drill these out and deal with the threads later? if i take the drill route, how do i make sure im not going to drill into the crankshaft? how do you guys get these screws out on engines that have been sitting the elements?

[Tom Scott]

Start by buying some Kroil: http://www.kanolabs.com/ Puts any other penetrating oil you can buy to shame.

I haven't worked on the model pto you have, but in general, drilling will be your last resort. Buy the Kroil and soak for a few days. See if there is a metric hex key that is just barely larger that you tap in if the standard size is too loose. If you can get a bite with a key, try turning it, but not so forceful that it strips out the hex. If it still won't turn, see if you can get a propane torch on the hub, heat is your friend. The idea is to apply the heat to the hub that the set screw is in to expand the hole the set screw is in. Try turning it again as soon as you remove the heat. Sometimes it can help to repeat the Kroil application as it cools, can help draw it in. Then heat and try again.

Screw extractor is last resort, can be difficult to get a good bite with them. There are ways like welding another bolt to the top but with such a small diameter that would be a challenge all on its own.

So, one last sales pitch, order some Kroil, it can make the difference. Good luck, keep us posted!

[ad356]

there is nothing to bite on. the screws were already in bad shape. nothing metric or SAE is going to work, tried every size. if i drill these things out my biggest concern is to not drill into the crankshaft. my friend has piles of cub cadet parts so even if needed another PTO it wouldn't be a big deal. really i would try to tap the PTO holes for a larger set screw so i could eliminate this from happening again. these set screws are fine for a machine that been stored indoors most of their life but they stink when its been sitting outside for 20+ years. really this is kind of an annoying problem. sitting outside this long hasnt done these screws any favors.

[ad356]

i think i need to see if i can get my hands on another clutch thats already been removed and see it i can measure the depth so i know where the bit must stop. then i would mark the bit with a piece of tape. trust me i looked inside those screws and there is no hex left to them. i know its not me because i never got a bite on them anyways. it took 20 minutes to even get the dirt and crap out of the screws so i could even see them. the biggest thing is i dont want to damage the crank.

[Paulf]

Andrew, the bottom of those set screws aren't that close to the crankshaft. You're more in danger of breaking the bit when you catch the side of the bearing. You can find the write up that I did on removing the PTO here: http://www.cubcadetman.com/cc/how-tos/2 ... et-pulley/ It also contains some pictures that should help.

[Paulf]

Oh, and several organizations have done studies of the best penetrating oil. The unanimous opinion is that a 50/50 combination of acetone and automatic transmission fluid is the best and cheapest you can get. Of course it's very flammable and should be used with caution.

[dag1450]

Wow....u got yourself a project Andrew! Just wondering.....u said this PTO sat outside for 20+ years. Looking at the bigger picture....is the engine that this PTO is married to gonna run? What other road blocks will u b facing fixing the engine? U could fight every single bolt u touch! Like I said....idk the status of this engine, if it's not running....it might b better to look for a different one.
Oh...and my take on the penitrat debate the two gentlemen mentioned....
Atf/acetone works good...if u have both on the shelf ...but kinda annoying to keep mixed, apply, store.
Kroil is known to b real good and super easy to apply.....just cost a few bucks

[dag1450]

Very nice write-up Paul!

[Paulf]

Thanks, Dave. I originally wrote if for myself and then decided to post it. I'm old enough that I sometimes forget the smaller details until it's too late. I still get in a hurry and forget to line up those slots for removing the set screws even after reading my reminder. It's too far from the computer to the shop. LOL

Paul

[BearKiller]

Every frozen screw removal is different, depending on location and access, among other factors.

I have NEVER in my entire mechanical life ever been able to successfully remove anything with so-called easy-outs, those tapered opposite-threaded extractor bits; they are so brittle that all they do is bite into the hole and then snap off, and then are so hard that it is impossible to then drill the broken easy-out; they should be against the law to own.

What I have sometimes found to work are left-handed drill bits; that is providing the stuck screw is right-handed.

If you have a straight shot to the screw, but it is too far for a normal bit to reach, there are also drill-bit extensions of various designs that will often save the day.

You have one thing in your favor in that an Allen/hex screw has the centered hex to guide the bit.

Choose a left-hand bit that is just smaller than the inner diameter of the threads and usually the bit will grab the screw just as it is about to break through and thus un-screw the screw.

All of this is assuming that you can get at the screw to drill.